1. Technical Field
The present disclosure is directed to a liquid crystal display device, and more particularly to, a flexible printed circuit board for use in a liquid crystal display device.
2. Discussion of Related Art
In general, a liquid crystal display (“LCD”) device refers to a device in which a thin film transistor (“TFT”) substrate and a color filter substrate, which are formed with an electric field generating electrode, are disposed in such a fashion that surfaces of the substrates formed with the electrode face each other. A liquid crystal layer is disposed between the two substrates, and then a voltage is applied across the electrodes of the substrates to generate an electric field to cause liquid crystals to be twisted, so that an image is displayed based on transmittance of light varying accordingly.
To this end, the liquid crystal display device includes a liquid crystal panel for displaying an image, a driving unit for driving the liquid crystal panel and a backlight unit for radiating light onto the liquid crystal panel. Currently, the backlight unit mainly employs, as a light source, a cylindrical linear light source lamp such as a cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp (EEFL), or the like. However, such a cylindrical linear light source lamp requires a light guide plate having a dimension corresponding to a tube diameter of the lamp and a reflective plate for allowing light to be emitted in all directions, which becomes an obstacle to slimness of products adopting a liquid crystal module.
Presently, to address this issue, the backlight unit employs a light emitting diode (“LED”) having a small thickness, which is driven with low power, as a light source. In the liquid crystal display employing the light emitting diode as a backlight, a flexible printed circuit board (“FPCB”) embedded with the LED is securely attached to a light guide plate or a bottom case by means of a double coated tape. Also, the FPCB embedded with the LED is joined by soldering to a main substrate for providing a driving voltage.
However, a conventional FPCB for the LED has a dual conductive layer structure including a power-supplying conductive layer connected to the LED and a soldering conductive layer connected to a solder pad. In the conventional FPCB for the LED, since a single conductive layer needs an adhesive layer and a cover layer, the soldering conductive layer, which is not used for the purpose of supplying power, may cause an increase in the thickness of the FPCB to thereby deteriorate flexibility of the FPCB and raise the manufacturing cost.